Scientific Investigations Report 2006–5290
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5290
Figure 9. Percentage of wells testing positive for coliform bacteria (A), and significantly different detection frequencies (p-value <0.002) of total coliform bacteria with respect to aquifer lithology (B). Graphs are based on data collected in 22 study units of the National Water-Quality Assessment program, 1993–2004.